Method and apparatus for advancing an instrument along an arbitrary path

ABSTRACT

An endoscope with guiding apparatus is described herein. A steerable endoscope is described having an elongate body with a manually or selectively steerable distal portion, an automatically controlled portion, a flexible and passively manipulated proximal portion, and an externally controlled and manipulatable tracking rod or guide. The tracking rod or guide is positioned within a guide channel within the endoscope and slides relative to the endoscope. When the guide is in a flexible state, it can conform to a curve or path defined by the steerable distal portion and the automatically controlled portion. The guide can then be selectively rigidized to assume that curve or path. Once set, the endoscope can be advanced over the rigidized guide in a monorail or “piggy-back” fashion so that the flexible proximal portion follows the curve held by the guide until the endoscope reaches a next point of curvature within a body lumen.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/087,100 entitled “Endoscope with Guiding Apparatus” filedMar. 1, 2002, which is a continuation-in-part of U.S. patent applicationSer. No. 09/969,927 entitled “Steerable Segmented Endoscope and Methodof Insertion” filed Oct. 2, 2001, which is a continuation-in-part ofU.S. patent application Ser. No. 09/790,204 entitled “SteerableEndoscope and Improved Method of Insertion” filed Feb. 20, 2001, whichclaims the benefit of priority to U.S. Provisional Patent ApplicationSer. No. 60/194,140 entitled the same and filed Apr. 3, 2000, all ofwhich are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates generally to endoscopes and endoscopicprocedures. More particularly, it relates to a method and apparatus tofacilitate insertion of a flexible endoscope along a tortuous path, suchas for colonoscopic examination and treatment.

BACKGROUND OF THE INVENTION

An endoscope is a medical instrument for visualizing the interior of apatient's body. Endoscopes can be used for a variety of differentdiagnostic and interventional procedures, including colonoscopy,bronchoscopy, thoracoscopy, laparoscopy and video endoscopy.

Colonoscopy is a medical procedure in which a flexible endoscope, orcolonoscope, is inserted into a patient's colon for diagnosticexamination and/or surgical treatment of the colon. A standardcolonoscope is typically 135-185 cm in length and 12-19 mm in diameter,and includes a fiberoptic imaging bundle or a miniature camera locatedat the instrument's tip, illumination fibers, one or two instrumentchannels that may also be used for insufflation or irrigation, air andwater channels, and vacuum channels. The colonoscope is inserted via thepatient's anus and is advanced through the colon, allowing direct visualexamination of the colon, the ileocecal valve and portions of theterminal ileum.

Insertion of the colonoscope is complicated by the fact that the colonrepresents a tortuous and convoluted path. Considerable manipulation ofthe colonoscope is often necessary to advance the colonoscope throughthe colon, making the procedure more difficult and time consuming andadding to the potential for complications, such as intestinalperforation. Steerable colonoscopes have been devised to facilitateselection of the correct path though the curves of the colon. However,as the colonoscope is inserted farther and farther into the colon, itbecomes more difficult to advance the colonoscope along the selectedpath. At each turn, the wall of the colon must maintain the curve in thecolonoscope. The colonoscope rubs against the mucosal surface of thecolon along the outside of each turn. Friction and slack in thecolonoscope build up at each turn, making it more and more difficult toadvance, withdraw, and loop the colonoscope. In addition, the forceagainst the wall of the colon increases with the buildup of friction. Incases of extreme tortuosity, it may become impossible to advance thecolonoscope all of the way through the colon.

Steerable endoscopes, catheters and insertion devices for medicalexamination or treatment of internal body structures are described inthe following U.S. patents, the disclosures of which are herebyincorporated by reference in their entirety: U.S. Pat. Nos. 4,543,090;4,753,223; 5,337,732; 5,337,733; 5,383,852; 5,487,757; 5,624,381;5,662,587; and 5,759,151.

SUMMARY OF THE INVENTION

Accordingly, an improved endoscopic apparatus is disclosed herein forthe examination of a patient's colon, other internal bodily cavities,and any other spaces within the body with minimal impingement uponbodily cavities or upon the walls of the organs. The disclosed apparatusmay also be employed for various surgical treatments of those regions,e.g., insufflation, drug delivery, biopsies, etc. A steerable endoscopehaving an elongate body with a manually or selectively steerable distalportion, an automatically controlled portion, which may be optionallyomitted from the device, a flexible and passively manipulated proximalportion, and an externally controlled and manipulatable tracking rod orguide is described below. The tracking rod or guide may be slidablypositioned within a guide channel or lumen within the endoscope or itmay be externally positionable such that the guide and the endoscope mayslide relative to one another along a rail or channel located along anexternal surface of the endoscope.

In operation, the steerable distal portion of the endoscope may be firstadvanced into a patient's rectum via the anus. The endoscope may besimply advanced, either manually or automatically by a motor, until thefirst curvature is reached. At this point, the steerable distal portionmay be actively controlled by the physician or surgeon to attain anoptimal curvature or shape for advancement of the endoscope. The optimalcurvature or shape is considered to be the path which presents the leastamount of contact or interference from the walls of the colon. In onevariation, once the desired curvature has been determined, the endoscopemay be advanced further into the colon such that the automaticallycontrolled segments of controllable portion follow the distal portionwhile transmitting the optimal curvature or shape proximally down theremaining segments of the controllable portion. The operation of thecontrollable segments will be described in further detail below.

In one variation, the guide is shorter than the full length of theendoscope, e.g., approximately the length of the controllable portion,and this shortened guide can be preloaded through the proximal end ofthe endoscope or through the handle of the endoscope. Once the guide isinserted, it may be advanced distally through the endoscope to thedistal tip of the endoscope. As the user advances the endoscopedistally, the automatically controlled segments of the proximalcontrollable portion propagate the selected curves down the endoscope,and the guide, in its flexible state, passively conforms to the shape ofthe desired pathway. Once the endoscope has advanced to a desiredposition, e.g. to a depth less than the length of the controllableportion of the endoscope, the user can rigidize the guide and maintainit at that depth (or axial position). The endoscope can then be furtheradvanced relative to the rigidized guide, sliding over the rigid guideand along the selected pathway. Thus, the surgeon or physician onlyneeds to lock the guide in position once. If the controllable region ofthe endoscope and the guide are each at least half of the length of theendoscope, the entire endoscope can conform to a selected pathway inthis manner. It is also possible to reposition the guide easily byrelaxing and/or unlocking it from its rigidized axial position and thenmoving the guide into its new position.

In an alternative variation, once the steerable distal portion has beensteered or positioned for advancement, the guide may be advanceddistally in its flexible state along or within the endoscope until itreaches a distal position, i.e., preferably some point distal of theflexible proximal portion. Regardless whether the optional controllableportion is omitted or not from the device, the guide may be advancednear or to the end of the distal portion. Once the guide has beenadvanced, it may directly attain and conform to the curvature or shapedefined by the steerable distal portion.

Preferably, the guide is advanced to the distal end of steerable distalportion or, if the controllable portion is included in the device, theguide may be advanced to the distal end of the controllable portion, orto some point between the two portions. The guide may be advanced to anydistal position as long as a portion of guide attains and conforms tothe optimal curvature or shape. Prior to advancing the endoscope overthe guide, the guide may be left in its flexible state or it may beoptionally rigidized, as discussed further below. If left in itsflexible state, the guide may possibly provide desirable column strengthto the endoscope as it is advanced through the colon over the guide. Itis preferable, however, that the guide is rigidized once it has attainedand conformed to the curvature. This allows the flexible proximalportion, i.e., the passive portion, to remain flexible and lightweightin structure. As the position of the guide is preferably rigidized andmaintained, the endoscope may then be advanced over the guide in amonorail or “piggy-back” fashion so that the flexible proximal portionfollows the curve held by the guide until the endoscope reaches the nextpoint of curvature.

In some variations, the process of alternately advancing the guide andthe endoscope may be repeated to advance the entire endoscope throughthe colon while the guide may be alternatively rigidized and relaxedwhile being advanced distally. While the endoscope is advanced throughthe colon, the physician or surgeon may stop the advancement to examinevarious areas along the colon wall using, e.g., an imaging bundlelocated at the distal end of the endoscope. During such examinations,the guide may be temporarily withdrawn from the endoscope to allow forthe insertion of other tools through the guide channel if there is noseparate channel defined within the endoscope for the guide. The guidemay also be withdrawn through the instrument to any location within thebody of the endoscope. In other words, the guide may be withdrawnpartially or removed entirely from the endoscope at any time, ifdesired, because there are no constraints which may limit the travel ofthe guide through the body of the endoscope. After a procedure has beencompleted on the colon wall, the tool may be withdrawn from the guidechannel and the guide may be reintroduced into the endoscope so that theendoscope may optionally be advanced once again into the colon.

A further variation on advancing the endoscope may use multiple guideswhich are alternately rigidized while being advanced distally along apath. Although multiple guides may be used, two guides are preferablyutilized. As the endoscopic device approaches a curvature, a first guidemay be advanced in a relaxed and flexible state towards the steerabledistal end of the device. While being advanced, the first guidepreferably conforms to the shape defined by the distal end and the firstguide may be subsequently rigidized to maintain this shape. The devicemay then be advanced further distally along the pathway while ridingover the rigidized first guide.

After the device has been advanced to its new position, a second guidemay also be advanced distally in its relaxed state through the device upto the distal end while the first guide is maintained in its rigidizedstate. The second guide may then conform to the new shape defined by thedistal end of the device and become rigidized to maintain this newshape. At this point, the first guide is also preferably maintained inits rigid state until the distal end of the device has been advancedfurther distally. The first guide may then be relaxed and advanced whilethe rigidity of the second guide provides the strength for advancing theguide. This procedure may be repeated as necessary for negotiating thepathway.

To withdraw the endoscope from within the colon, the procedure above maybe reversed such that the withdrawal minimally contacts the walls of thecolon. Alternatively, the guide may simply be removed from the endoscopewhile leaving the endoscope within the colon. Alternatively, the guidemay be left inside the endoscope in the relaxed mode. The endoscope maythen be simply withdrawn by pulling the proximal portion to remove thedevice. This method may rub or contact the endoscope upon the walls ofthe colon, but any impingement would be minimal.

The selectively steerable distal portion can be selectively steered orbent up to a fall 180° bend in any direction. A fiberoptic imagingbundle and one or more illumination fibers may extend through the bodyfrom the proximal portion to the distal portion. The illumination fibersare preferably in communication with a light source, i.e., conventionallight sources, which may be positioned at some external location, orother sources such as LEDs. Alternatively, the endoscope may beconfigured as a video endoscope with a miniaturized video camera, suchas a CCD camera, positioned at the distal portion of the endoscope body.The video camera may be used in combination with the illuminationfibers. Optionally, the body of the endoscope may also include one ortwo access lumens that may optionally be used for insufflation orirrigation, air and water channels, and vacuum channels, etc. Generally,the body of the endoscope is highly flexible so that it is able to bendaround small diameter curves without buckling or kinking whilemaintaining the various channels intact. The endoscope can be made in avariety of other sizes and configurations for other medical andindustrial applications.

In some variations the endoscope may optionally include a suction devicethat can withdraw air or other gases, e.g. gases used for insufflatingthe interior of a colon. In the example of insufflating a colon, theinsufflated gas may be trapped within regions of the colon due to thesacculation and movement of the colon walls. To facilitate removal ofthese gases, the suction device may be utilized to withdraw thesetrapped gases as the endoscope is advanced or withdrawn through thecolon.

The suction device may comprise a suction tube positioned within theendoscope and connected to a suction port defined along the endoscopeouter surface at a location proximal of the distal tip. The suction portcan apply suction at some distance from the tip of the endoscope so thatthe suction does not interfere with insufflation or other activities atthe distal end of the endoscope. In one variation, the suction port islocated in the distal half of the endoscope, approximately one-quarterdown the length of the insertable portion of the endoscope, e.g., 40 to50 cm from the steerable tip. Some variations may apply suctioncontinuously, while others allow the user to selectively controlapplication of the suction.

The optional controllable portion is composed of at least one segmentand preferably several segments which may be controllable via a computerand/or controller located at a distance from the endoscope. In onevariation, approximately half of the length of the endoscope iscomprised of controllable segments. Each of the segments preferably havean actuator mechanically connecting adjacent segments to allow for thecontrolled motion of the segments in space. The actuators driving thesegments may include a variety of different types of mechanisms, e.g.,pneumatic, vacuum, hydraulic, electromechanical motors, drive shafts,etc. If a mechanism such as a flexible drive shaft were utilized, thepower for actuating the segments would preferably be developed by agenerator located at a distance from the segments, i.e., outside of apatient during use, and in electrical and mechanical communication withthe drive shaft. Alternatively, segments could be actuated by push-pullwires or tendons, e.g. Bowden cables, that bend segments by distributingforce across a segment, as described in “Tendon-Driven Endoscope andMethods of Insertion” filed Aug. 27, 2002 (attorney docket number514812000125), which is incorporated in its entirety by reference.

A proximal portion comprises the rest of the endoscope and preferably amajority of the overall length of the device. The proximal portion ispreferably a flexible tubing member that may conform to an infinitevariety of shapes. It may also be covered by a polymeric coveringoptionally extendable over the controllable portion and the steerabledistal portion as well to provide a smooth transition between thecontrollable segments and the flexible tubing of the proximal portion.The controllable portion may be optionally omitted from the endoscope. Amore detailed description on the construction and operation of thesegments may be found in U.S. patent application Ser. No. 09/969,927entitled “Steerable Segmented Endoscope and Method of Insertion” filedOct. 2, 2001, which has been incorporated by reference in its entirety.

A proximal handle may be attached to the proximal end of the proximalportion and may include imaging devices connected to the fiberopticimaging bundle for direct viewing and/or for connection to a videocamera or a recording device. The handle may be connected to otherdevices, e.g., illumination sources and one or several luer lockfittings for connection to various instrument channels. The handle mayalso be connected to a steering control mechanism for controlling thesteerable distal portion. The handle may optionally have the steeringcontrol mechanism integrated directly into the handle, e.g., in the formof a joystick, conventional disk controller using dials or wheels, etc.An axial motion transducer may also be provided for measuring the axialmotion, i.e., the depth change, of the endoscope body as it is advancedand withdrawn. The axial motion transducer can be made in many possibleconfigurations. As the body of the endoscope slides through thetransducer, it may produce a signal indicative of the axial position ofthe endoscope body with respect to the fixed point of reference. Thetransducer may use various methods for measuring the axial position ofthe endoscope body.

The guide is generally used to impart a desired curvature initiallydefined by the steerable portion and/or by the optional controllableportion to the passive proximal portion when the endoscope is advanced.If held or advanced into the steerable portion, the guide is preferablyadvanced to or near the distal tip of the portion. It is also used toimpart some column strength to the proximal portion in order to maintainits shape and to prevent any buckling when axially loaded. Preferably,the guide is slidably disposed within the length of the endoscope bodyand may freely slide entirely through the passive proximal portion,through the controllable portion, and the steerable distal portion. Theextent to which the guide may traverse through the endoscope body may bevaried and adjusted according to the application, as described above.Furthermore, the proximal end of the guide may be routed through aseparate channel to a guide controller which may be used to control theadvancement and/or withdrawal of the guide and which may also be used toselectively control the rigidity of the guide as controlled by thephysician.

The structure of the guide may be varied according to the desiredapplication. The following descriptions of the guide are presented aspossible variations and are not intended to be limiting in theirstructure. For instance, the guide may be comprised of two coaxiallypositioned tubes separated by a gap. Once the guide has been placed andhas assumed the desirable shape or curve, a vacuum force may be appliedto draw out the air within the gap, thereby radially deforming one orboth tubes such that they come into contact with one another and locktheir relative positions.

Another variation on the guide is one which is rigidizable by atensioning member. Such a guide may be comprised of a series ofindividual segments which are rotatably interlocked with one another inseries. Each segment may further define a common channel through which atensioning member may be positioned while being held between a proximaland a distal segment. During use, the tensioning member may be slackenedor loosened enough such that the guide becomes flexible enough to assumea shape or curve defined by the endoscope. When the guide is desirablysituated and has assumed a desired shape, the tensioning member may thenbe tensioned, thereby drawing each segment tightly against one anotherto hold the desired shape.

Another variation may use a guide which is comprised of interlockingball-and-socket type joints which are gasketed at their interfaces. Sucha design may utilize a vacuum pump to selectively tighten and relax theindividual segments against one another. Other variations may includealternating cupped segments and ball segments, a series of collinearsleeve-hemisphere segments, as well as other designs which may interfitwith one another in series. Such a guide may be tightened and relaxedeither by tensioning members or vacuum forces.

A further variation on the guide is a coaxially aligned stiffeningmember. This assembly may include a first subassembly comprising anumber of collinearly nested segments which may be held by a tensioningmember passing through each segment. The first subassembly may berigidized from a flexible or flaccid state by pulling on this tensioningmember. A second subassembly may comprise a number of annular segmentsalso collinearly held relative to one another with one or moretensioning members passing through each annular segment. The secondsubassembly preferably defines a central area in which the first nestedsubassembly may be situated coaxially within the second subassembly. Thefirst subassembly is preferably slidably disposed relative to the secondsubassembly thereby allowing each subassembly to be alternately advancedin a flexible state and alternately rigidized to allow the othersubassembly to be advanced. This design presents a small cross-sectionrelative to the endoscope or device through which it may be advanced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a representation of a conventional endoscope in use.

FIG. 2A shows a variation of an endoscopic device of the presentinvention.

FIGS. 2B and 2C show side sectional views of another variation of thepresent invention.

FIG. 3A shows a side view of an endoscopic device variation with theouter layers removed to reveal a guiding apparatus disposed within.

FIGS. 3B and 3C show cross-sectional views of various examples forobstructing the guide lumen of the endoscope.

FIGS. 4A to 4C show cross-sectional views of various examples of guidingapparatus which may be used to guide an endoscope.

FIGS. 5A and 5B show the cross-sectioned end and side views,respectively, of a guiding apparatus with a vacuum-actuated rigidizingvariation.

FIGS. 6A and 6B show the cross-sectioned end and side views,respectively, of a guiding apparatus with a tensioning or pre-tensionedelement for rigidizing the guide.

FIGS. 7A and 7B show the cross-sectioned end and side views,respectively, of a guiding apparatus with a segmented vacuum-actuatedrigidizing variation.

FIGS. 8A and 8B show the cross-sectioned end and side views,respectively, of a guiding apparatus with interconnecting jointedsegments for rigidizing the guide.

FIGS. 9A to 9C show end, side, and cross-sectioned views, respectively,of another variation on the guiding apparatus.

FIG. 10 shows the cross-sectioned side view of another variation on theguiding apparatus having alternating bead and sleeve segments.

FIG. 11A shows a side view of a nested guiding apparatus which is partof a coaxial stiffening assembly.

FIG. 11B shows a side view of an annular guiding apparatus which is alsopart of the coaxial stiffening assembly.

FIG. 11C shows the combination of the guides from FIGS. 11A and 11B.

FIGS. 12A and 12B illustrate a representative example of advancing theendoscope along a tortuous pathway using a single rigidizing step.

FIGS. 13A to 13H illustrate a representative example of advancing anendoscope through a patient's colon using a guiding apparatus to assistin advancing the endoscope.

FIGS. 14A and 14B show a variation on the withdrawal of the endoscopewith or without the guiding apparatus for the selective treatment ofsites along the patient's colon.

FIGS. 15A to 15C illustrate a representative example of advancing anendoscope through a tortuous path using the coaxial guiding apparatusshown in FIGS. 11A to 11C.

FIGS. 16A to 16E illustrate another variation of advancing an endoscopethrough a tortuous path using multiple guiding apparatuses.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a prior art colonoscope 10 being employed for acolonoscopic examination of a patient's colon C. The colonoscope 10 hasa proximal handle 16 and an elongate body 12 with a steerable distalportion 14. The body 12 of the colonoscope 10 has been lubricated andinserted into the colon C via the patient's anus A. Utilizing thesteerable distal portion 14 for guidance, the body 12 of the colonoscope10 has been maneuvered through several turns in the patient's colon C tothe ascending colon G. Typically, this involves a considerable amount ofmanipulation by pushing, pulling and rotating the colonoscope 10 fromthe proximal end to advance it through the turns of the colon C. Afterthe steerable distal portion 14 has passed, the wall of the colon Cmaintains the curve in the flexible body 12 of the colonoscope 10 as itis advanced. Friction develops along the body 12 of the colonoscope 10as it is inserted, particularly at each turn in the colon C. Because ofthe friction, when the user attempts to advance the colonoscope 10, thebody 12′ tends to move outward at each curve, pushing against the wallof the colon C, which exacerbates the problem by increasing the frictionand making it more difficult to advance the colonoscope 10. On the otherhand, when the colonoscope 10 is withdrawn, the body 12″ tends to moveinward at each curve taking up the slack that developed when thecolonoscope 10 was advanced. When the patient's colon C is extremelytortuous, the distal end of the body 12 becomes unresponsive to theuser's manipulations, and eventually it may become impossible to advancethe colonoscope 10 any farther. In addition to the difficulty that itpresents to the user, tortuosity of the patient's colon also increasesthe risk of complications, such as intestinal perforation.

FIG. 2A shows a variation of the steerable endoscope 20 of the presentinvention. The endoscope 20 has an elongate body 21 with a manually orselectively steerable distal portion 24, an automatically controlledportion 28, which may be optionally omitted from the device, a flexibleand passively manipulated proximal portion 22, and an externallycontrolled and manipulatable tracking rod or guide 36 which may beslidably positioned within the endoscope 20.

The selectively steerable distal portion 24 can be selectively steeredor bent up to a fall 180° bend in any direction 26, as shown in thefigure. A fiberoptic imaging bundle 40 and one or more illuminationfibers 42 may extend through the body 21 from the proximal portion 22 tothe distal portion 24. Alternatively, the endoscope 20 may be configuredas a video endoscope with a miniaturized video camera, such as a CCDcamera, positioned at the distal portion 24 of the endoscope body 21.The images from the video camera can be transmitted to a video monitorby a transmission cable or by wireless transmission where images may beviewed in real-time or recorded by a recording device onto analogrecording medium, e.g., magnetic tape, or digital recording medium,e.g., compact disc, digital tape, etc. Optionally, the body 21 of theendoscope 20 may include one or two access lumens 38 that may optionallybe used for illumination fibers for providing a light source,insufflation or irrigation, air and water channels, and vacuum channels.Generally, the body 21 of the endoscope 20 is highly flexible so that itis able to bend around small diameter curves without buckling or kinkingwhile maintaining the various channels intact. When configured for useas a colonoscope, the body 21 of the endoscope 20 may range typicallyfrom 135 to 185 cm in length and about 13-21 mm in diameter. Theendoscope 20 can be made in a variety of other sizes and configurationsfor other medical and industrial applications.

The optional controllable portion 28 is composed of at least one segment30, and preferably several segments 30, which may be controllable via acomputer and/or controller located at a distance from the endoscope 20.Each of the segments 30 preferably has an actuator mechanicallyconnecting adjacent segments 30 to allow for the controlled motion ofthe segments 30 in space. The actuators driving the segments 30 mayinclude a variety of different types of mechanisms, e.g., pneumatic,hydraulic, electromechanical motors, “off board” powered drive shafts,tendons, etc. A proximal portion 22 comprises the rest of the endoscope20 and preferably a majority of the overall length of the device 20.Proximal portion 20 is preferably a flexible tubing member which mayconform to an infinite variety of shapes. It may also be covered by apolymeric covering 39 optionally extendable over controllable portion 28and steerable distal portion 24 as well to provide a smooth transitionbetween the controllable segments 30 and the flexible tubing of proximalportion 22. The proximal portion 22 may be made from a variety ofmaterials such as thermoset and thermoplastic polymers which are usedfor fabricating the tubing of conventional endoscopes.

A proximal handle 32 may be attached to the proximal end of the proximalportion 22. The handle 32 may include an ocular 33 connected to thefiberoptic imaging bundle 42 for direct viewing. The handle 32 mayotherwise have a connector for connection to a video camera, e.g., a CCDcamera, or a recording device. The handle 32 may be connected to anillumination source 43 by an illumination cable 44 that is connected toor continuous with the illumination fibers 42. One or several luer lockfittings 34 may be located on the handle 32 and connected to the variousinstrument channels.

The handle 32 is connected to an electronic motion controller 45 by wayof a controller cable 46. A steering control 47 may be connected to theelectronic motion controller 45 by way of a second cable 48 or it mayoptionally be connected directly to the handle 32. Alternatively, thehandle may have the steering control mechanism integrated directly intothe handle, e.g., in the form of a joystick, conventional diskcontrollers such as dials or wheels, etc. The steering control 47 allowsthe user to selectively steer or bend the selectively steerable distalportion 26 of the body 21 in the desired direction. The steering control47 may be a joystick controller as shown, or other known steeringcontrol mechanism. The electronic motion controller 45 controls themotion of the automatically controlled proximal portion 28 of the body21. The electronic motion controller 45 may be implemented using amotion control program running on a microcomputer or using anapplication-specific motion controller. Alternatively, the electronicmotion controller 45 may be implemented using, e.g., a neural networkcontroller.

An axial motion transducer 49 may be provided for measuring the axialmotion, i.e., the depth change, of the endoscope body 21 as it isadvanced and withdrawn. The axial motion transducer 49 can be made inmany possible configurations. For example, the axial motion transducer49 in FIG. 2A is configured as a ring 49 that may surround the body 21of the endoscope 20. The axial motion transducer 49 is preferablyattached to a fixed point of reference, such as the surgical table orthe insertion point for the endoscope 20 on the patient's body. As thebody 21 of the endoscope 20 slides through the axial motion transducer49, it produces a signal indicative of the axial position of theendoscope body 21 with resect to the fixed point of reference and sendsa signal to the electronic motion controller 45 by telemetry or by acable. The axial motion transducer 49 may use optical, electronic ormechanical methods to measure the axial position of the endoscope body21.

Similarly, when the endoscope body 21 is withdrawn proximally, each timethe endoscope body 21 is moved proximally by one unit, each section inthe automatically controlled proximal portion 28 is signaled to assumethe shape of the section that previously occupied the space that it isnow in. The curve propagates distally along the length of theautomatically controlled proximal portion 28 of the endoscope body 21,and the shaped curve appears to be fixed in space, as the endoscope body21 withdraws proximally. Alternatively, the segments of controlledportion 28 could be made to become flaccid and the withdrawal would thenbe passive.

Whenever the endoscope body 21 is advanced or withdrawn, the axialmotion transducer 49 detects the change in position and the electronicmotion controller 45 propagates the selected curves proximally ordistally along the controllable portion 28 of the endoscope body 21 tomaintain the curves in a spatially fixed position. The axial motiontransducer 49 also allows for the incrementing of a current depth withinthe colon C by the measured change in depth. This allows the endoscopebody 21 to be guided through tortuous curves without putting unnecessaryforce on the wall of the colon C. As mentioned above, such a segmentedbody 30 within the controllable portion 28 may be actuated by a varietyof methods. One method involves the use of electromechanical motorswhich may be individually mounted on each segment 30 to move thesegments 30 relative to one another. Each segment 30 preferably definesat least one lumen running through it to provide an access channelthrough which wires, optical fibers, air and/or water channels, variousendoscopic tools, or any variety of devices and wires may be routedthrough.

A more detailed description on the construction and operation of thesegments may be found in U.S. patent application Ser. No. 09/969,927entitled “Steerable Segmented Endoscope and Method of Insertion” filedOct. 2, 2001, which has been incorporated by reference in its entirety.

The guide 36 is generally used to impart a desired curvature initiallydefined by the steerable distal portion 24 and/or by the optionalcontrollable portion 28 to the passive proximal portion 22 when theendoscope 20 is advanced. If the guide 36 is advanced into the steerabledistal portion 24, guide 36 is preferably advanced to or near the distaltip of the portion 24. The guide 36 may also be used partly to impartsome column strength to the proximal portion 22 in order to maintain itsshape and to prevent any buckling when axially loaded, such as when theendoscope 20 is advanced through a patient's colon. Construction of anendoscope 20 with the use of the guide 36 not only simplifies thecontrol systems involved but it also represents a cost efficient device.Operation of the endoscope 20 with guide 36 will be discussed, in detailbelow.

Preferably, the guide 36 is slidably disposed within the length of theendoscope body 21 and may freely slide entirely through the passiveproximal portion 22, through the optional controllable portion 28, ifutilized in the endoscope, and the steerable distal portion 24. Guide 36may also be withdrawn through the instrument to any location within thebody of endoscope 20. Moreover, guide 36 may be removed entirely fromendoscope 20, if desired e.g., to accommodate additional working tools.In other words, there are preferably no constraints which may limit thetravel of guide 36 within the body of endoscope 20.

Guide 36 may be advanced through proximal handle 32; alternatively,guide 36 may also be routed through a separate channel 37 dedicated tothe guide 36. Channel 37 is preferably attached to endoscope 20 near aproximal end of the instrument, such as a location off the proximalportion 22, and leads to a guide controller 41 which may be used toadvance and/or withdraw guide 36 through endoscope 20. Guide controller41 may also be used to selectively rigidize and relax guide 36 duringuse within a patient. Having guide controller 41 and proximal handle 32separated may allow for the ease of use for the physician manipulatingthe endoscope 20. To aid in advancing guide 36 through endoscope 20, apulley mechanism may be affixed within the steerable distal portion 24through which a pull wire may extend over to connect the distal end ofthe guide 36 to a location outside the endoscope 20 for manipulation bythe physician.

To facilitate the movement of guide 36 through endoscope body 21, alubricious covering or coating may be applied over at least a majorityof the length of guide 36 or onto the inner surface of the lumen throughwhich guide 36 traverse, or both. Such coverings may include variouspolymers and plastics, e.g., PTFE, etc., which may simply cover theguide 36 length or which may be heatshrunk, coated, or bonded onto guide36, depending upon the material used. The extent to which guide 36traverses through the endoscope body 21 may be varied and adjustedaccording to the application.

FIGS. 2B and 2C show sectional partial views of a variation of theendoscope that is capable of single-step use of the guide. In thesevariations, the axial length of the guide 51 is shorter than theinsertable length of the endoscope 23. The endoscope body 21 includes asteerable distal tip 24 and a proximal controllable region 28 that iscomprised of flexible segments 30. Approximately half of the length ofthe endoscope body may be composed of controllable segments 30, and theremaining proximal part of the endoscope is flexible passive portion 22.The length of the guide 51 is approximately half that of the endoscopebody 23. Although the guide 51 is freely slidable within lumen 50 of theendoscope 23 in the variation shown, the guide 51 may be preloadedthrough the distal end of the endoscope 23 before insertion into thebody. Alternatively, the guide 51 could be positioned as describedabove. The guide 51 can be rigidized and held in place by the tensioningwire 36. The combination of steerable distal tip 24, controllableproximal portion 28 and guide 51 in this variation of the inventionsimplifies the use of the rigidizable guide 51 because the guide 51 onlyhas to be rigidized and locked into position once.

FIG. 2C shows another, slightly magnified, sectional view of theendoscope of FIG. 2B. This view illustrates an optional suction device53, e.g., a negative pressure pump device, which may be fluidlyconnected to suction port 202 through suction tube 204. Suction device53 is preferably located externally of the patient during use. Becauseinsufflated air or gas may be trapped within regions of the colon due tothe sacculation and movement of the colon walls, the suction device 53may be used to facilitate removal of these gases as the endoscope isadvanced or withdrawn through the colon. The suction port 202 shown ispreferably located at some point proximal of distal end 24, e.g.,approximately one quarter of the length of the endoscope body 23. Thissuction port can be located virtually anywhere along the length of theendoscope, but it is preferably located such that it does hot interferewith the insufflation process at or near the distal tip.

FIG. 3A shows an isometric view of a length of the endoscope 20, in thisexample part of the proximal portion 22, with a section of the endoscopebody 20 removed for clarity. As seen, a representative illustration ofthe guide 36 may be seen disposed within guide channel or lumen 50within the proximal portion 22. Lumen 50 may be an existing workingchannel, i.e., an access channel for other tools, or it may be adesignated channel for guide 36 depending upon the desired application.Guide 36 may be inserted within guide channel 50 through the endoscopehandle 32 and pushed proximally through the remainder of the device, asseen in FIG. 2A; or preferably, it may be pushed proximally or pulleddistally, as necessary, through a separate guide controller 41, asdiscussed above. Although guide 36 is shown in this variation as beingslidably disposed interiorly of endoscope body 20, it may also bedisposed exteriorly of the body 20 to slide along a guide rail orexterior channel in other variations.

If guide 36 is located within a dedicated channel, such as lumen 50, thedistal end of this channel is preferably closed or blocked at somedistal location, e.g., within steerable distal portion 24 or withinoptional controllable portion 28, to prevent the influx of bodily fluidswithin lumen 50. Because an enclosed lumen 50 would further preventcontact of bodily fluids with guide 36, the amount of cleaning orsterilization of guide 36 is reduced.

If lumen 50 were left as an open channel, additional sterilization orcleaning and disinfecting of guide 36 and lumen 50 may be necessary.Alternatively, lumen 50 may be left as an open channel but configured tohave optional closing mechanisms, as shown in the examples of FIGS. 3Band 3C, taken from FIG. 3A. FIG. 3B shows an end view of a trap or door54 which is held within the body of the instrument and which may berotated about a pivot 56 in the direction of the arrow to close accessto lumen 50. Trap 54 may be closed during insertion of the instrumentwithin a patient and then optionally opened to allow for working toolsto be inserted therethrough. FIG. 3C shows another example where lumen50 may be obstructed by an inflatable balloon 59 which may selectivelyexpand to completely obstruct the passageway. Balloon 59 may be made ofconventional materials and may be held within a compartment or step 58such that lumen 50 is unobstructed when balloon 59 is deflated. Theseexamples merely present variations and are not meant to limit the scopeof the invention. Alternative designs and variations are intended to bewithin the scope of the present invention.

FIGS. 4A to 4C show variations on possible cross-sections 4A-4A, 4B-4B,and 4C-4C, respectively, taken from FIG. 3A. FIG. 4A shows a simplifiedcross-section 22′ of a guide 36 having a circular diameter slidablydisposed within proximal portion 22. As seen, guide 36 may be slidablypositioned within channel 50′, which may also be used as a workingchannel upon removal of guide 36 during, e.g., a colonoscopy procedure,for providing access for various instruments or tools to a treatmentsite. FIG. 4B shows another possible variation in cross-section 22″where guide 36 is positioned within channel 50″. The variation of theproximal portion in cross-section 22″ may include a number of accesslumens 52 optionally formed within the body of the device 20. Theselumens 52 may run through the length of device 20 and may be used forvarious applications, e.g., illumination fibers, laparoscopic tools,etc. Although three lumens 52 are shown in the figure, any number ofchannels as practically possible may be utilized depending upon theapplication at hand. FIG. 4C shows another variation in cross-section22′″. In this variation, guide 36′ may be formed into a semi-circular orelliptical shape to slide within a similarly shaped channel 50′″. Inthis example, proximal portion 22′″ also includes a working channel 52′which may be shaped accordingly to fit within the body 22′″ along withchannel 50′″ to maintain a working channel without having to removeguide 36′. In any of the above examples, the working or guide channelsare preferably integral structures within the body of endoscope 20.Having an integral structure eliminates the need for a separate lumenedstructure, e.g., a separate sheath, through which guide 36 or any othertools may be inserted. Another variation utilizing multiple channels andmultiple guides will be described in further detail below. Thesevariations are not intended to be limiting but are merely presented aspossible variations. Other structures and variations thereof may berecognized by one of skill in the art and are intended to be within thescope of the claims below.

The structure of the guide may be varied according to the desiredapplication. The following description on the guide is presented aspossible variations and are not intended to be limiting in theirstructure. FIGS. 5A and 5B show cross-sectioned end and side views,respectively, of a guiding apparatus variation which is rigidizable by avacuum force applied within the guide. It is preferable that the guideis selectively rigidizable, i.e., when the guide assumes a shape orcurve in a flexible state, the guide may be rigidized to hold that shapeor curve for a predetermined period of time. Although the endoscopestructure of the present invention may utilize a guide which remains ina relatively flexible shape, it is preferable to have the guide beselectively rigidizable.

Guide 60 may be comprised of two coaxially positioned tubes, outer tube62 and inner tube 64, which are separated by a gap 66 between the twotubes. Inner tube 64 may define an access lumen 68 throughout the lengthof the tube to provide a channel for additional tools or other accessdevices. Both tubes 62, 64 are preferably flexible enough to be bentover a wide range of angles and may be made from a variety of materialssuch as polymers and plastics. They are also preferably flexible enoughsuch that either the outer tube 62, inner tube 64, or both tubes areradially deformable. Once guide 60 has been placed and has assumed thedesirable shape or curve, a vacuum force may be applied to draw out theair within gap 66. This vacuum force may radially deform inner tube 64and bring it into contact with the inner surface of outer tube 62 ifinner tube 64 is made to be relatively more flexible than outer tube 62.Alternatively, if outer tube 62 is made to be relatively more flexiblethan inner tube 64, outer tube 62 may be brought into contact with theouter surface of inner tube 64.

In another variation, tubes 62, 64 may both be made to be flexible suchthat they are drawn towards one another. In yet another variation, whichmay be less preferable, a positive force of air pressure or a liquid,e.g., water or saline, may be pumped into access lumen 68. The positivepressure from the gas or liquid may force the walls of inner tube 64radially into contact with the inner surface of outer tube 62. In any ofthese variations, contact between the two tubular surfaces will lock thetubes 62, 64 together by frictional force and make them less flexible.An elastomeric outer covering 69, or similar material, may optionally beplaced upon the outer surface of outer tube 62 to provide a lubricioussurface to facilitate the movement of guide 60 within the endoscopicdevice. An example of a device similar to guide 60 is discussed infurther detail in U.S. Pat. No. 5,337,733, which has been incorporatedherein by reference in its entirety.

Another variation on the guide is shown in FIGS. 6A and 6B which showcross-sectioned end and side views, respectively, of a guiding apparatusvariation 70 which is rigidizable by a tensioning member 76. Tensionedguide 70 is shown comprised of a series of individual segments 72 whichare rotatably interlocked with one another in series. Each segment 72may contact an adjoining segment 72 along a contacting lip 78. Eachsegment 72 may further define a channel therethrough which, collectivelyalong with the other segments 72, form a common channel 74 throughout amajority of the length of guide 70. Segments 72 may be comprised of avariety of materials suitable for sustaining compression forces, e.g.,stainless steel, thermoplastic polymers, plastics, etc.

Proximal and distal segments of guide 70 may hold respective ends oftensioning member 76, which is preferably disposed within common channel74 through guide 70. Tensioning member 76 may be connected to atensioning housing located externally of a patient. During use when theguide is advanced distally through an endoscope of the presentinvention, tensioning member 76 is preferably slackened or loosenedenough such that guide 70 is flexible enough to assume a shape or curvedefined by the endoscope. When guide 70 is desirably situated and hasassumed a desired shape, tensioning member 76 may be tensioned. Thistightening or tensioning of member 76 will draw each segment 72 tightlyagainst one another along each respective contacting lip 78 such thatthe guide 70 becomes rigid in assuming the desired shape. A lubriciouscovering, e.g., elastomers, etc., may be optionally placed over at leasta majority of guide 70 to facilitate movement of the guide 70 relativeto the endoscopic device. A similar concept and design is discussed infurther detail in U.S. Pat. No. 5,624,381, which has been incorporatedherein by reference in its entirety.

FIGS. 7A and 7B show cross-sectioned end and side views, respectively,of a guiding apparatus variation 80 which is rigidizable by a vacuumforce which interlocks individual segments 82. Each segment 82 may beadjoined with adjacent segments by interlocking ball-and-socket typejoints which are preferably gasketed at the interfaces 86 of eachconnection. Within each segment 82, with the exception of the distalsegment, may be defined a channel which is narrowed at one end andflared at the opposite end. Collectively when the segments 82 areadjoined into the structure of guide 80, each of the individual channelsform a common channel 84 which extends through at least a majority ofthe segments 82 along the length of guide 80. At the proximal end ofguide 80 a vacuum pump, which is preferably located externally of thepatient, is fluidly connected to common channel 84. In use, once guide80 is manipulated in its flexible state within the endoscope to assumethe desired shape or curve, ambient pressure may exist within commonchannel 84. When the rigid shape of guide 80 is desired, the pump maythen be used to create a negative pressure within common channel 84 andthis negative pressure draws each segment 82 into tight contact with oneanother to maintain the desired shape. When the vacuum force isreleased, each segment 82 would also be released and would thereby allowthe guide 80 to be in its flexible state for advancement or withdrawal.Guide 80 may further be surrounded by an elastomeric or lubriciouscovering to aid in the advancement or withdrawal of the guide 80 withinthe endoscopic device.

FIGS. 8A and 8B show cross-sectioned end and side views, respectively,of yet another guiding apparatus variation 90 which is optionallyrigidizable by either a vacuum force or a tensioning member whichinterlocks individual segments 92. Segment 92 may be in the form of asegmented design with two opposed cups having a common channel 94defined therethrough. Between each segment 92 are ball segments 96 whichinterfits along a contact rim or area 97 within each adjacent segment92. Ball segments 96 preferably contact adjacent cupped segments 96within receiving channels 98 defined in each cup. When manipulated inits flexible state, guide 90 may be advanced or withdrawn or made toassume a desired shape or curve. When guide 90 is to be placed into itsrigidized shape, a vacuum force or tensioning member 99 may be utilizedin the guide 90 in similar manners as described above. Moreover, guide90 may similarly be surrounded by an elastomeric or lubricious coveringto aid in the advancement and withdrawal of the guide 90.

FIGS. 9A and 9B show representative end and side views, respectively, ofanother guiding apparatus variation 100. This variation 100 comprisesindividual segments 102 having a uniform sleeve section 104 incombination with an integrated curved or hemispherical section 106. Eachsegment 102 is collinearly aligned with one another with the sleevesection 104 receiving the curved section 106 of an adjacent segment 102,as shown in FIG. 9C, which is the cross-section of guide 100 from FIG.9B. The adjacent segments 102 may rotate relative to one another overthe sleeve-hemisphere interface while maintaining a common channel 108through the guide 100. A tensioning member 110 may pass through channel108 along the length of guide 100 for compressing the individualsegments 102 against one another when the entire guide 100 is rigidized.

FIG. 10 shows the cross-section of another variation 120 of therigidizable guide apparatus. Representative segments are showncomprising spherical bead segments 122 alternating with sleeve segments124. Each of the bead and sleeve segments 122, 124, respectively, mayhave a channel defined therethrough which allows for a tensioning member126 to be run through the length of guide 120. The alternating segmentsallow for the rotation of the adjacent segments while the tensioningmember 126 allows for the compression of the segments against oneanother when the guide 120 is to be rigidized in much the same manner asdescribed above.

An alternative variation on the rigidizable guide is illustrated inFIGS. 11A to 11C, which show a stiffening assembly having separaterigidizable coaxially positioned guides. FIG. 11A shows a representativenumber of nested segments 132 in nested stiffening assembly 130. Eachnested segment 132 may be in a number of different configurations, e.g.,ball socket joints, stacked ring-like segments, etc., with a tensioningmember 134 passing through each of the segments 132. For use with nestedassembly 130, an annular stiffening assembly 140 may be seen in FIG.11B. Annular assembly 140, of which only a few representative segmentsare shown, are comprised in this variation of annular segments 142 whichmay be stacked or aligned one atop each other. At least one tensioningmember 144, and preferably at least two, may be passed through each ofthe annular segments 142. A central area 146 is defined in each annularsegment 142 such that nested stiffening assembly 130 may be slidinglyplaced within the central area 146 defined by the annular stiffeningassembly 140. FIG. 11C shows the stiffening assembly 130 slidinglypositioned within annular stiffening assembly 140 to form the coaxiallyaligned stiffening assembly 150. Use of coaxial assembly 150 will bedescribed in further detail below.

FIGS. 12A and 12B illustrate a variation of the endoscope advancingthrough a tortuous path, using an endoscope similar to the variation ofFIG. 2B. FIG. 12A shows a pathway with multiple turns 210, resembling alength of the colon. The distal half of the device 212 comprises asteerable distal portion 24 and a controllable proximal portion 28. Theguide 51 is slidably held within a lumen within the endoscope in therelaxed state. As the device 212 is advanced into the pathway 210, theuser steers the distal tip 24, and the controllable segments 30 followthe curve selected by the user, navigating the chosen pathway. While inthe relaxed state, the guide 51 may passively assume the shape taken bythe distal portion 24 and the controllable proximal portion 28 as theyare steered along the path. Usually, the user may rigidize and/or “lock”the guide 51 to assume the curve of the selected pathway before thecontrollable proximal portion 28 has advanced beyond the first curve220. After being stiffened and locked into position, the endoscope cancontinue moving distally while still maintaining the selected pathway,since the passive flexible proximal region 22 of the endoscope slidesover the rigid guide 51 and conforms to its shape, as shown in FIG. 12B.

After rigidizing the guide, the user can continue to steer the distalend 24 as it is advanced, and the curves of the selected pathway arepropagated proximally down the controllable segments 30 as the endoscopemoves forward. This variation of the device is capable of conforming toa selected pathway over the entire length of the endoscope, despitehaving a shorter guide 51 and controllable portion 28, since thecombined length of the guide 51 and the controllable portion ispreferably equal to the length of the endoscope.

In operation, any of the guiding apparatus as described above or onerecognized by a person of skill in the art to be suitable for such useas described herein may be utilized. FIGS. 13A to 13H illustrate arepresentative method of advancing a colonscopic device 20 as describedherein with a representative guide 36 for advancement into a patient'scolon C. As seen in FIG. 13A, the steerable distal portion 24 ofcolonoscope 20 may be first advanced into the patient's rectum via anusA. The device 20 may be simply advanced, either manually orautomatically by a motor, until the first curvature is reached oralternatively until the segments of controllable portion 28 are withincolon C. At this point, the steerable distal portion 24 may be activelycontrolled by the physician or surgeon to attain an optimal curvature orshape for advancement of device 20. The optimal curvature or shape isconsidered to be the path which presents the least amount of contact orinterference from the walls of colon C. If the optional controllableportion 28 is used with the colonoscopic device 20, once the advancementposition 160 has been determined, the device 20 may be advanced furtherinto the sigmoid colon S such that the automatically controlled segmentsof controllable portion 28 follow the distal portion 24 whiletransmitting the optimal curvature or shape proximally down theremaining segments of controllable portion 28.

Alternatively, once steerable distal portion 24 has been steered orpositioned for advancement 160, guide 36 may be advanced distally in itsflexible state along or within device 20 until it reaches a distalposition, i.e., some point distal of the flexible proximal portion 22and preferably to the distal end of the device 20, as shown in FIG. 13B.Preferably, guide 36 is advanced to the distal end of steerable distalportion 24 or to the distal end of the optional controllable portion 28,if utilized, or to some point therebetween. Guide 36 may be advanced toany distal position as long as a portion of guide 36 attains the optimalcurvature or shape. Prior to advancing the device 20 over guide 36, theguide 36 may be left in its flexible state or it may be optionallyrigidized, as discussed above. If left in its flexible state, guide 36will still provide desirable column strength to the device 20 as it isadvanced through colon C over the guide 36. It is preferable, however,that guide 36 is rigidized once it has attained and conformed to thecurvature. As the position of guide 36 is preferably rigidized andmaintained, the device 20 may then be advanced over the guide 20 in amonorail or “piggy-back” fashion so that the flexible proximal portion22 follows the curve held by guide 36 until the device 20 reaches thenext point of curvature. The following description discusses the use ofthe optional controllable portion 28; however, this portion 28 may beomitted from the device 20.

As shown from FIGS. 13B to 13C, the curve is maintained by guide 36until the steerable distal portion 24 has been advanced to the juncturebetween the sigmoid colon S and the descending colon D. At this point,the distal portion 24 may be actively steered by the physician using avariety of visualization techniques, e.g., steering via an optionalimaging bundle 40 located at the distal end of the device 20. Once theoptimal curve or shape has been determined, the device 20 maybe advancedto position 160. As the device is moved distally, if the controllableportion 28 is utilized, portion 28 will automatically follow the pathset by the distal portion while the flexible proximal portion followsthe device 20 along the curvature defined by the guide 36. Otherwise, ifcontrollable portion 28 is omitted, guide 36 will have its curvaturedefined solely by steerable distal portion 24. Once the junction betweenthe sigmoid colon S and descending colon D has been traversed by thesteerable distal portion 24 and the optional controllable portion 28,the guide may then be relaxed and advanced distally along the device 20in its flexible state until it reaches the distal position in the device20. As the guide 36 is advanced, it will attain and conform to a newcurvature defined by the steerable distal portion 24 and/or thecontrollable portion 28, as shown in FIG. 13D.

Having attained a new curvature, guide 36 may again be rigidized tomaintain this shape. While the guide 36 maintains this shape, the device20 may be advanced further distally along the descending colon D withthe help of the rigidized guide 36 in the piggy-back manner describedabove to define the path for the flexible proximal portion 22 and toprevent excessive contact with the walls of colon C. As shown in FIG.13E, the device 20 has been advanced past the left (splenic) flexureF_(l) in the manner described above until the optional controllableportion 28 has attained the optimal curvature. The guide 36 may berelaxed again and advanced further distally in its flexible state, asshown from FIGS. 13E to 13F.

After guide 36 has assumed the desired curvature defined by the distalportion 24 and/or controllable portion 28, as shown in FIG. 13F, it mayagain be rigidized and the device 20 may then be advanced through thetransverse colon T and around the right (hepatic) flexure F_(r) in muchthe same manner as described above and as shown in FIG. 13G. Once thedistal portion 24 and the optional controllable portion 28 hascontrollably negotiated past the right (hepatic) flexure F_(r), theposition of guide 20 may again be maintained while guide 36 is relaxedonce again and advanced distally to assume the new curvature defined bydistal portion 24 and/or controllable portion 28, as shown in FIG. 13H.After guide 36 is optionally rigidized again, device 20 may be advanced160 completely within the ascending colon G towards the cecum E for acomplete examination of the colon C with minimal complication andeffort.

While the device 20 is advanced through the colon C, the physician orsurgeon may stop the advancement to examine various areas along thecolon wall using, e.g., the imaging bundle 40. During such examinations,the guide 36 may be temporarily withdrawn manually or automatically fromthe device 20 to allow for the insertion of other tools through theguide channel 50. After a procedure has been completed on the colonwall, the tool may be withdrawn from guide channel 50 and guide 36 maybe reintroduced into the device 20 so that the device may optionally beadvanced once again into colon C.

To withdraw device 20 from within the colon C, the procedure above maybe reversed, as shown in FIG. 14A, such that the withdrawal 162minimally contacts the walls of colon C. Alternatively, guide 36 maysimply be removed from device 20, as shown in FIG. 14B, while leavingdevice 20 within colon C. The device 20 may simply be withdrawn bypulling the proximal portion 22 to remove the device 20. This method mayrub or contact the device 20 upon the walls of colon C, but anyimpingement would be minimal.

An alternative method of advancing an endoscope through a tortuous pathmay be seen in FIGS. 15A to 15C by using the rigidizable guide assembly150 seen from FIG. 11C. FIG. 15A shows a pathway to be negotiated byendoscopic device 172. The pathway may represent a portion of colon 170.As device 172 is desirably steered to assume a curve, nested stiffeningassembly 130 may be advanced distally within device 172 to distal end174 while in a relaxed state. Alternatively, nested assembly 130 may beadvanced in the flexible, relaxed state along with the distal end 174.

Once the curve has been selected, nested assembly 130 may be stiffenedto maintain its shape. At this point, annular stiffening assembly 140may be advanced over nested assembly 130 towards distal end 174. Onceassembly 140 has assumed the curve defined by assembly 130, annularassembly 140 may then be rigidized and nested assembly 130 may berelaxed into its flexible state, as shown in FIG. 15B. Then the distalend 174 may be further advanced with or without assembly 130 while beingpushed along the curve defined by rigidized annular assembly 140, asshown in FIG. 15C. Once distal end 174 of device 172 has negotiated thecurve, nested assembly 130, after being advanced to distal end 174, maythen be rigidized again and annular assembly 140 may be relaxed andadvanced again over assembly 130 and so on until the desired treatmentlocation has been reached within the body.

Another alternative variation on advancing an endoscope through atortuous path may be seen in FIGS. 16A to 16E. This variation usesmultiple guides which may be alternately rigidized while being advanceddistally along the path. FIG. 16A shows a portion of the curved pathwayin colon 170 with endoscope 180 being advanced therethrough. Multipleguides may be used in this variation, but preferably two guides areutilized, as described below. Any one of the rigidizable guidevariations discussed herein may be used solely or in combination withdifferent types of guides in the same device 180. Each guide may beadvanced within its own lumen defined within the endoscope, or they mayalso share a common dedicated lumen.

As device 180 approaches a curvature of colon 170, first guide 184 maybe advanced towards the steerable distal end 182. While being advanced,first guide 184 is in a relaxed and flexible state allowing it toconform to the shape defined by the distal end 182. Having been advancedto distal end 182, as shown in FIG. 16B, first guide 184 is rigidized tomaintain the shape defined by the steerable distal end 182. Device 180may then be advanced further distally into colon 170 while riding overrigidized first guide 184.

After device 180 has been further advanced to a new position, secondguide 186 may also be advanced distally in its relaxed state throughdevice 180 up to the distal end 182 while first guide 184 is preferablystill rigidized, as shown in FIG. 16C. As second guide 186 advances, itmay conform to a new shape defined by device 180. Second guide 186 maythen be rigidized to hold its shape. First guide 184 may be relaxed butits rigid shape is preferably also maintained while the distal end 182of device 180 is further advanced distally through colon 170, as shownin FIG. 16D.

After device 180 has been advanced distally, first guide 184 may berelaxed and advanced through device 180 up to distal end 182 while therigidity of second guide 186 is maintained, as shown in FIG. 16E. Secondguide 186 may be relaxed and then advanced in its flexible statedistally through device 180 and so on. This process may be repeated asdevice 180 is required to negotiate arbitrarily tortuous paths.

Although the endoscope of the present invention has been described foruse as a colonoscope, the endoscope can be configured for a number ofother medical and industrial applications. In addition, the presentinvention can also be configured as a catheter, cannula, surgicalinstrument or introducer sheath that uses the principles of theinvention for navigating through tortuous body channels. The presentinvention may also be used for industrial applications such asinspection and exploratory applications within tortuous regions, e.g.,machinery, pipes, etc.

In a variation of the method that is particularly applicable tolaparoscopy or thoracoscopy procedures, the steerable endoscope can beselectively maneuvered along a desired path around and between organs ina patient's body cavity. The distal end of the endoscope may be insertedinto the patient's body cavity through a natural opening, through asurgical incision or through a surgical cannula, introducer, or trocar.The selectively steerable distal portion can be used to explore andexamine the patient's body cavity and to select a path around andbetween the patient's organs. The electronic motion controller inconjunction with the tracking rod can be used to control theautomatically controlled proximal portion to follow the selected pathand allow the rest of the body to follow the tracking rod and, ifnecessary, to return to a desired location using the three-dimensionalmodel in the electronic memory of the electronic motion controller.Modification of the above-described assemblies and methods for carryingout the invention, and variations of aspects of the invention that areobvious to those of skill in the art are intended to be within the scopeof the claims.

1-34. (canceled)
 35. A method of advancing an instrument along anarbitrary path, comprising: selectively steering a distal portion of theinstrument to assume a selected shape along an arbitrary path; advancingthe instrument distally while configuring a controllable portion of theinstrument to assume the selected shape of the distal portion, whereinthe controllable portion is proximal of the distal portion; advancing anelongate guide along the instrument such that a portion of the guideconforms to and assumes the selected shape; and maintaining a positionof the guide while advancing the instrument along the guide such that aproximal portion of the instrument assumes the selected shape defined bythe guide, wherein the elongate guide is freely slidable along theinstrument such that advancing of the instrument along the guide isunconstrained.
 36. The method of claim 35 further comprising measuring adepth change of the instrument while advancing the instrument distally.37. The method of claim 36 further comprising incrementing a currentdepth by the depth change.
 38. The method of claim 35 further comprisingreleasing the position of the guide and further advancing the guidealong the instrument.
 39. The method of claim 35 further comprisingwithdrawing the guide from the instrument.
 40. The method of claim 35wherein the elongate guide is advanced along by passing the instrumentthrough a lumen within the elongate guide.
 41. The method of claim 35wherein the distal portion of the instrument selectively assumes asecond shape when the instrument is advanced along the guide.
 42. Themethod of claim 35 wherein maintaining the position of the guidecomprises rigidizing the guide such that the guide rigidly assumes aposition of the selected shape.
 43. The method of claim 42 whereinrigidizing the guide comprises applying tension to a tensioning memberdisposed within the guide such that a plurality of adjacent segmentscomprising the guide are compressed.
 44. The method of claim 42 whereinrigidizing the guide comprises applying a compressive force to anexterior of the elongate guide such that a plurality of adjacentsegments comprising the guide are compressed.
 45. An apparatus forinsertion into a body cavity, comprising: an elongate body having aproximal portion and a selectively steerable distal portion and defininga lumen therebetween, the steerable distal portion being configurable toassume a selected shape along an arbitrary path; an elongate guidehaving a proximal section, a distal section, and a length therebetween,the guide being slidably disposed without constraint over the elongatebody to selectively support the elongate body, wherein the guide isconfigured to conform to and selectively maintain the selected shapeassumed by the steerable distal portion, and wherein the proximalportion of the elongate body when advanced distally is configured toconform to the selected curve maintained by the guide.
 46. The apparatusof claim 45 further comprising a controllable portion located proximallyof the distal portion, wherein the controllable portion is configured topropagate the selected shape to the controllable portion.
 47. Theapparatus of claim 46 wherein the selectively steerable distal portionis configurable via a control located externally of the body cavity. 48.The apparatus of claim 45 wherein the proximal section comprises aflexible tubular member.
 49. The apparatus of claim 48 wherein theelongate guide comprises a plurality of pivotally connected segments.50. The apparatus of claim 45 wherein the elongate guide is configuredto assume the selected shape when the guide is in a flexible state andwherein the guide is further configured to maintain the selected shapewhen the guide is in a rigidized state.
 51. The apparatus of claim 50wherein the elongate guide is configured to selectively rigidize alongthe length of the guide to maintain the selected shape in the rigidizedstate.
 52. The apparatus of claim 50 wherein the proximal section of theelongate guide is in communication with a guide controller forselectively rigidizing the guide along its length.
 53. The apparatus ofclaim 50 wherein the elongate guide comprises a plurality of adjacentsegments each defining a channel therethrough such that a common channelis defined through the length of the guide.
 54. The apparatus of claim53 further comprising a tensioning member slidably extending through theplurality of adjacent segments such that applying a force to thetensioning member compresses the adjacent segments together.
 55. Theapparatus of claim 53 wherein the elongate guide is configured tomaintain a position of adjacent segments relative to each other uponapplying a compressive force to an exterior of the plurality of adjacentsegments.
 56. The apparatus of claim 55 further comprising an expandableballoon.
 57. The apparatus of claim 45 further comprising a tubularcovering disposed over at least a majority of the length of the elongateguide.
 58. A method of advancing an instrument along an arbitrary path,comprising: selectively steering a distal portion of the instrument toassume a selected shape along an arbitrary path; advancing an elongateguide along the instrument such that a portion of the guide conforms toand assumes the selected shape; maintaining a position of the guidewhile advancing the instrument along the guide such that a proximalportion of the instrument assumes the selected shape defined by theguide; and measuring a depth change of the instrument while advancingthe instrument distally, wherein the elongate guide is freely slidablealong the instrument such that advancing of the instrument along theguide is unconstrained.
 59. The method of claim 58 wherein, prior toadvancing the elongate guide along the instrument, further comprisingadvancing the instrument distally while configuring a controllableportion of the instrument to assume the selected shape of the distalportion, wherein the controllable portion is proximal of the distalportion.
 60. The method of claim 58 further comprising incrementing acurrent depth by the depth change.
 61. The method of claim 58 furthercomprising releasing the position of the guide and further advancing theguide along the instrument.
 62. The method of claim 58 furthercomprising withdrawing the guide from the instrument.
 63. The method ofclaim 58 wherein the elongate guide is advanced along by passing theinstrument through a lumen within the elongate guide.
 64. The method ofclaim 58 wherein the distal portion of the instrument selectivelyassumes a second shape when the instrument is advanced along the guide.65. The method of claim 58 wherein maintaining the position of the guidecomprises rigidizing the guide such that the guide rigidly assumes aposition of the selected shape.
 66. The method of claim 65 whereinrigidizing the guide comprises applying tension to a tensioning memberdisposed within the guide such that a plurality of adjacent segmentscomprising the guide are compressed.
 67. The method of claim 65 whereinrigidizing the guide comprises applying a compressive force to anexterior of the elongate guide such that a plurality of adjacentsegments comprising the guide are compressed.
 68. An apparatus forinsertion into a body cavity, comprising: an elongate body having aselectively steerable distal portion, a controllable portion locatedproximally of the distal portion, and a lumen defined therebetween, thesteerable distal portion being configurable to assume a selected shapealong an arbitrary path; an elongate guide having a proximal section, adistal section, and a length therebetween, the guide being slidablydisposed without constraint over the elongate body to selectivelysupport the elongate body, wherein the guide is configured to conform toand selectively maintain the selected shape assumed by the steerabledistal portion, and wherein the controllable portion of the elongatebody when advanced distally is configured to propogate the selectedshape to the contollable portion and conform to the selected curvemaintained by the guide.
 69. The apparatus of claim 68 wherein theselectively steerable distal portion is configurable via a controllocated externally of the body cavity.
 70. The apparatus of claim 68wherein the proximal section comprises a flexible tubular member. 71.The apparatus of claim 70 wherein the elongate guide comprises aplurality of pivotally connected segments.
 72. The apparatus of claim 68wherein the elongate guide is configured to assume the selected shapewhen the guide is in a flexible state and wherein the guide is furtherconfigured to maintain the selected shape when the guide is in arigidized state.
 73. The apparatus of claim 72 wherein the elongateguide is configured to selectively rigidize along the length of theguide to maintain the selected shape in the rigidized state.
 74. Theapparatus of claim 72 wherein the proximal section of the elongate guideis in communication with a guide controller for selectively rigidizingthe guide along its length.
 75. The apparatus of claim 72 wherein theelongate guide comprises a plurality of adjacent segments each defininga channel therethrough such that a common channel is defined through thelength of the guide.
 76. The apparatus of claim 75 further comprising atensioning member slidably extending through the plurality of adjacentsegments such that applying a force to the tensioning member compressesthe adjacent segments together.
 77. The apparatus of claim 75 whereinthe elongate guide is configured to maintain a position of adjacentsegments relative to each other upon applying a compressive force to anexterior of the plurality of adjacent segments.
 78. The apparatus ofclaim 77 further comprising an expandable balloon.
 79. The apparatus ofclaim 68 further comprising a tubular covering disposed over at least amajority of the length of the elongate guide.
 80. An apparatus forinsertion into a body cavity, comprising: an elongate body having aproximal portion, a selectively steerable distal portion, and a lumendefined therebetween, the steerable distal portion being configurable toassume a selected shape along an arbitrary path; an elongate guidehaving a proximal section, a distal section, and a length therebetween,the proximal section comprising a flexible tubular member, the guidecomprising a plurality of pivotally connected segments and beingslidably disposed without constraint over the elongate body toselectively support the elongate body, wherein the guide is configuredto conform to and selectively maintain the selected shape assumed by thesteerable distal portion, and wherein the proximal portion of theelongate body when advanced distally is configured to conform to theselected curve maintained by the guide.
 81. The apparatus of claim 80further comprising a controllable portion located proximally of thedistal portion, wherein the controllable portion is configured topropagate the selected shape to the controllable portion.
 82. Theapparatus of claim 81 wherein the selectively steerable distal portionis configurable via a control located externally of the body cavity. 83.The apparatus of claim 80 wherein the elongate guide is configured toassume the selected shape when the guide is in a flexible state andwherein the guide is further configured to maintain the selected shapewhen the guide is in a rigidized state.
 84. The apparatus of claim 83wherein the elongate guide is configured to selectively rigidize alongthe length of the guide to maintain the selected shape in the rigidizedstate.
 85. The apparatus of claim 83 wherein the proximal section of theelongate guide is in communication with a guide controller forselectively rigidizing the guide along its length.
 86. The apparatus ofclaim 83 wherein the plurality of pivotally connected segments of theelongate guide further comprises a plurality of adjacent segments eachdefining a channel through the guide such that a common channel isdefined through the length of the guide.
 87. The apparatus of claim 86further comprising a tensioning member slidably extending through theplurality of adjacent segments such that applying a force to thetensioning member compresses the adjacent segments together.
 88. Theapparatus of claim 86 wherein the elongate guide is configured tomaintain a position of adjacent segments relative to each other uponapplying a compressive force to an exterior of the plurality of adjacentsegments.
 89. The apparatus of claim 88 further comprising an expandableballoon.
 90. The apparatus of claim 80 further comprising a tubularcovering disposed over at least a majority of the length of the elongateguide.
 91. A method of advancing an instrument along an arbitrary path,comprising: selectively steering a distal portion of the instrument toassume a selected shape along an arbitrary path; advancing an elongateguide along the instrument by passing the instrument through a lumenwithin the elongate guide, such that a portion of the guide conforms toand assumes the selected shape; and maintaining a position of the guidewhile advancing the instrument along the guide such that a proximalportion of the instrument assumes the selected shape defined by theguide, wherein the elongate guide is freely slidable along theinstrument such that advancing of the instrument along the guide isunconstrained.
 92. The method of claim 91 wherein, prior to advancingthe elongate guide along the instrument, further comprising advancingthe instrument distally while configuring a controllable portion of theinstrument to assume the selected shape of the distal portion, whereinthe controllable portion is proximal of the distal portion.
 93. Themethod of claim 91 further comprising measuring a depth change of theinstrument while advancing the instrument distally.
 94. The method ofclaim 93 further comprising incrementing a current depth by the depthchange.
 95. The method of claim 91 further comprising releasing theposition of the guide and further advancing the guide along theinstrument.
 96. The method of claim 91 further comprising withdrawingthe guide from the instrument.
 97. The method of claim 91 wherein thedistal portion of the instrument selectively assumes a second shape whenthe instrument is advanced along the guide.
 98. The method of claim 91wherein maintaining the position of the guide comprises rigidizing theguide such that the guide rigidly assumes a position of the selectedshape.
 99. The method of claim 98 wherein rigidizing the guide comprisesapplying tension to a tensioning member disposed within the guide suchthat a plurality of adjacent segments comprising the guide arecompressed.
 100. The method of claim 98 wherein rigidizing the guidecomprises applying a compressive force to an exterior of the elongateguide such that a plurality of adjacent segments comprising the guideare compressed.